Oil originating from pipelines, ships, wells, railroads, trucks and the like often is spilled due to accidents and is introduced into the environment. Such spills may occur in or adjacent to bodies of water such as lakes, oceans, streams and rivers. The potential for environmental damage is great and it is advantageous to remove the spilled oil from the water as soon as possible to prevent its dispersion to greater areas and to minimize the damage to life forms which depend on uncontaminated water.
Typically, oil skimmers are used to remove the oil in bodies of water caused by contamination. Such skimmers are usually maintained in storage locations where they can quickly be deployed to the accident area and introduced into the water so as to quickly remove the oil from the contaminated water.
The oil which is accidentally introduced to bodies of water may be oil of a single or uniform consistency or it may comprise relatively lighter and relatively heavier consistencies. The oil of lighter consistency generally flows well and the removal of such oil from the water proceeds without undue difficulty using presently available technology. Typically, such light oil is removed by a revolving brush or other rotating member which comes into contact with the light oil and to which the light oil adheres. The member is rotated past a scraper or other oil removal device which contacts the member and thereby mechanically removes the adhered oil. The oil removed falls into a collecting trough where it is subsequently pumped to a storage location.
Where oil of relatively heavier consistency is also introduced to the water, problems arise in removing both the heavier oil and the light oil. The heavier oil does not flow well and although it does adhere to the rotating member, such as to the bristles of a rotating brush, if it is removed with the light oil into a collection trough, the heavier oil tends to clog the trough and to resist flow to the pump removal area. The clogging of the collection trough by the heavier oil also prevents the flow of lighter oil from smoothly proceeding to the pump removal area. This is not satisfactory and, heretofore, a single skimmer could not satisfactorily remove both oils of light and heavier consistencies.
Generally, when the oil introduced into the environment contains oil of lighter and heavier consistencies, two skimmers are used. The first skimmer is used to remove the light oil and the second skimmer is used to remove the heavy oil. The use of two skimmers is expensive and increases the time necessary to deploy the skimmers and remove the oil when time is very important in expediently removing the contaminating oil from the environment.
While it has been proposed to apply steam or other heat to the heavier oil collected in order to improve its flow characteristics and to allow it to be removed with the light oil, the application of steam or other heat requires a steam or heat generator of one type or another located near the area of skimmer deployment. This is expensive and complicated.